The Durham Council of Garden Clubs was founded in 1929 in federation with the National Garden Club and The Garden Club of North Carolina, Inc.
The Council served more than eight decades as the umbrella group for garden clubs and junior garden clubs in Durham, NC. Today, Durham Garden Clubs continue the same mission of philanthropic projects of preservation, conservation, education and beautification under District 9 of the Garden Clubs of NC.

Saturday, June 30, 2012

How Gross Are the Grubs?

While there are several kinds of grubs that damage turfgrass, most are
relatively harmless as adults. The most notable exception is the
destructive import, the Japanese Beetle. Once it emerges from the ground
where it has been gnawing the roots of your plants, its life of
destruction goes into high gear.

A typical white grub is a whitish color with a hard brown head
capsule and a darker terminal segment. Entomologists can identify the
species of grub by inspecting the pattern of hairs on this anal
segment. White grubs are legged and their bodies curved in a
characteristic C-shape.While the life cycle of the different
species varies, typically the adult female deposits her eggs in the
soil, where they hatch into grubs. These larvae
then feed on the roots of plants, doing damage to crops and to
turfgrass. In the winter, they burrow deeper into the earth to avoid
freezing, then tunnel upward again in spring. Some species may spend
more than a single year as larvae, others emerge in the next spring or
summer as mature beetles.In the lawn, a large infestation of
grubs can destroy substantial sections of grass by eating away the roots
so that the sod can be easily lifted from the soil. When the grass is
rolled away, the grubs can clearly be seen just below the sod. Often,
additional damage is done to the lawn when animals such as skunks and raccoons dig holes to hunt for the yummy and nutritious grubs. This may reduce the grub population, but it doesn't help the grass!It
is this damage to lawns that has been the greatest motivation for the
typical homeowner to make war on the grubs. It was once common to apply
insecticides such as diazinon
to the lawn, but such poisons kill indiscriminately and are now
discouraged; diazinon is now largely prohibited in the United States
for non-agricultural use, but newer insecticides such as imidacloprid are still available. Less toxic biological controls are becoming more widely used. Spores of the bacterium Bacillus popilliae, often sold under the name of Milky Spore, can inoculate
a lawn with bacterial milky disease, which effects the grubs of
Japanese Beetles. Another method of control is the introduction of
several species of parasitic nematodes such as Steinernema carpocapsae applied to the lawn.

The
problem with most these methods (Milky Spore is said to be specific to
the Japanese Beetle) is their lack of target specificity. A wide range
of insects and other arthropods, many beneficial, live in the soil,
particularly in their larval stages. Widespread application of toxic
substances can do serious ecological damage. This is also true of the
use of nematodes. Even if a species of nematodes
only attacks grubs of the Scarabaeidae family, there are thousands of
beetle species that might be affected, most of them harmless.Few
prevalent species of grubs grow up to be serious problems to gardeners.
The common June beetle, for example, is usually little more than an
annoyance as it flies against window screens at night. But in North
America, a foreign invader has now changed the stakes. Early in the
last century, the Japanese BeetlePopillia japonica was
accidentally introduced into an environment where it was free from
natural enemies. It has since spread westward, establishing itself in
most areas east of the Mississippi.

This
insect, while destructive as a grub, becomes an even worse pest as an
adult. The beetles can accumulate in vast numbers to feed on their
preferred species of vegetation, and they are capable of serious damage,
sometimes defoliating entire plants. Their method of feeding on leaves
is skeletonization, consuming the tissue between the veins. They will
also feed on flowers and fruit. A few of their preferred targets are roses, grapes, plums and corn, as well as birch and maple trees.As the Japanese Beetle enters a region, the use of both grub controls and insecticides
rises in response as homeowners, gardeners and farmers combat the
infestation. Nontoxic methods have been tried. Pheromone traps, which
attract the beetles into a trap from which they are unable to escape,
have had mixed results. Many people insist that the traps attract more
beetles to a location than were originally present. This has been my
own experience. While I trapped thousands of beetles, the number of
them feeding on my plants only seemed to increase.So far, alas,
the beetles seem to be winning, and causing unfortunate collateral
damage among related species as humans attempt to control them.